the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 19 Dec 2025
Natural disturbances increasingly affect Europe’s most mature and carbon-rich forests
Abstract. Europe's forests store nearly 40 PgC and provide a critical carbon sink of ~0.2 PgC yr-1, yet climate-driven disturbances increasingly threaten this capacity. Although disturbance rates from windthrow and bark beetle outbreaks have risen in recent decades, it remains unclear whether these events increasingly affect the oldest and largest trees, which store a disproportionate share of carbon. Here, we combine three decades of satellite-derived disturbance maps with spatially explicit data on forest age, biomass, and species composition to reveal patterns of structural selectivity across Europe. We show that natural disturbances have shifted toward older, carbon-rich stands, with disturbed forest area > 60 years old nearly tripling since 2010 (from 0.38 to 1.06 Mha). This structural shift is most pronounced in spruce-dominated regions of Central Europe (effect size = 1), where compound heat and drought events have amplified susceptibility to bark beetles. Biomass losses from natural disturbances in spruce forests increased eightfold between the early (2011–2016) and recent (2017–2023) periods. Trend-based projections indicate that, if current patterns of structural selectivity persist, natural disturbances could expose biomass carbon stocks equivalent to approximately 20 % of Europe’s contemporary forest carbon sink by 2040 (~0.05 PgC yr -1 or ~0.7 PgC cumulative). Our findings reveal a previously unquantified vulnerability: climate-driven disturbances increasingly affect forest structures with high per-hectare carbon stocks, amplifying disturbance-related carbon exposure and weakening the long-term effectiveness of Europe’s forest carbon sink. Adaptive management strategies that promote structural and compositional diversification in high-risk regions will be critical to stabilise forest carbon storage under continued climate change.
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- RC1: 'Comment on egusphere-2025-6288', Bogdan Brzeziecki, 18 Feb 2026 reply
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- 1
Alba Viana-Soto
Henrik Hartmann
Marco Patacca
Viola H. A. Heinrich
Katja Kowalski
Maurizio Santoro
Wanda De Keersmaecker
Ruben Van De Kerchove
Martin Herold
Cornelius Senf
Europe’s forests store vast amounts of carbon, but climate-driven disturbances are becoming more frequent. By combining satellite records with information on forest age and structure, we show that recent disturbances increasingly affect the oldest and most carbon-rich forests, particularly spruce forests in Central Europe. This emerging pattern puts long-accumulated carbon at risk and may reduce the long-term climate benefits provided by Europe’s forests.
Europe’s forests store vast amounts of carbon, but climate-driven disturbances are becoming more...
General assessment
The subject of this work is the impact of natural disturbances (such as insect outbreaks and windstorms) and planned harvesting operations on the current condition and future development of European forests, in the context of their vital role in climate mitigation. The authors focused on basic tree stand’s features such as age, dominant tree species, aboveground biomass and spatial structure. In order to achieve the main paper’s goal, they first compiled and standardized relevant data from various sources and streams (in form of various thematic maps covering the entire area of Europe) and then processed them using advanced statistical methods and tools. They compared two periods: 2011-2016 (serving as a reference) and 2017-2023. Based on the obtained results, they concluded that, compared to the reference period, recently, not only the rate of disturbances and the damage they cause increased, but also the ecological profile of the affected stands changed significantly, i.e. current disturbances increasingly affect mature forest stands and forest areas distinguished by high carbon stocks (with particular emphasis on spruce-dominated forests). As pointed out by authors, structural shifts toward older, higher-biomass, and more homogeneous stands substantially amplify future carbon exposure and negatively affect the mitigation role of forests in relation to climate change. Their discussion highlights, among other things, the fact that reducing the future susceptibility of forests to increasingly frequent and intense disturbances "will likely require coordinated management of species composition, structural complexity, and spatial heterogeneity."
In general, the results obtained in this work are not surprising and confirm what has been known for a long time, such as the fact that older (and denser) and structurally less diverse stands are more susceptible to disturbances, like hurricane winds or harmful insects. Similarly, the idea of creating forest stands distinguished by diverse species composition and age structure is certainly not new and has been formulated many times before.
The above comments do not in any way lower my high assessment of this work, which, in my opinion, presents a very high scientific level. It is based on extensive empirical material. It employs a significant number of modern and advanced methodological approaches. The obtained results are presented in a clear manner, including aesthetically pleasing and easily readable figures. Thanks to the analyses conducted, the authors were able to quantitatively characterize the phenomena they studied, including estimating the magnitude of the reduction in the rate of carbon uptake by European forests by 2040, depending on the adopted scenario for future disturbance regimes.
Thus, in my opinion, the potential for significant improvement of this interesting, important and necessary work is not big. Possibly, a certain dissatisfaction may arise from the lack of an attempt to explain in more detail the reasons for the change in the characteristics of the stands affected by studied disturbance types that took place between the reference period and the present one. Was it the result of a change in the disturbance regimes and their vital parameters? Or the result of a change in approach from the forest management side, often forced by external circumstances? It would also have been possible to discuss in more detail the consequences of the obtained results from the point of view of what the optimal strategy for using forests should be for the purpose of mitigating climate change. I am thinking here, for example, of the recently strongly promoted concept of proforestation, i.e. withdrawing managed stands - including young and very young stands - from utilisation, placing them under strict protection and allowing them to “age” naturally. Does such a strategy make much sense, taking into account the results of this work and its forecasts for further developments?
Minor concerns
From a formal point of view, I wouldn't have too many critical comments about this paper, either. Perhaps in a few cases certain issues could be made a little clearer, especially from the point of view of a reader who is less familiar with the methods used in the work. Some examples from this field, including few editorial propositions, are given below:
Line 22. Add space after „area”.
Line 27. “expose” or maybe simply “release into the atmosphere”?
Line 38. “climate-sensitive” or maybe “climate-induced” or “climate-driven”?
Line 53-54. Maybe: “These trends are likely to persist as climate change continues” (to avoid repetition of “continue”).
Lines 55-56. Maybe: “such as windstorms Vivian and Wiebke (in 1990), Lothar and Martin (in 1999), and Klaus (in 2009).”?
Line 64. “are driven primarily by expanding spatial footprints”. Not very clear.
Line 72. What about: “with spatially explicit data on forest age…”?
Lines 85-87. It is not quite obvious for me how “the 30 m binary disturbance maps were aggregated to 100 m resolution”. Did you use information from nine 30 m x 30 m pixels (81,000 m2) per one 100 m x 100 m pixel (10,000 m2)?
Line 95. I am just not very sure if the term “disturbance” is appropriate in the case of (planned) harvesting activities. Maybe from the pure ecological point of view…
Line 95. “the forest age and biomass products” or just “the forest age and biomass data”?
Line 114. Is “20 members” clear enough?
Line 116. “forest fraction at 100 m pixel”?
Line 124. “Forest age was obtained from the 20-member GAMIv3.0 ensemble”. Repetition, see Line 114.
Line 128. indicated?
Line 134. “X ′ and Y′ are independent copies of X and Y”. Not very clear what is meant here by “independent copies”.
Line 143. “we summarised uncertainty across the 20-member ensembles”. I am not sure what is meant by “member ensembles”. Could you be more specific here?
Line 156. “ 20 biomass members”. Not very clear what does it mean.
Lines 164-167. Repetition. See lines 122-126.
Line 168. “each member of the 20-realisation biomass ensemble”. Not very clear, see comment to Line 156.
Lines 179-181. Repetition. See lines 122-126.
Lines 232-234. Partly repetition. Besides, this fragments fits better the Methods chapter. What does it actually mean: “higher values”? higher than what?
Line 348. Maybe “…the recent biomass loss scenario…”?
Fig. 5. “Biomass Loss: Natural Disturbance/Harvest (Late – Early)” or “Biomass Loss: Natural Disturbance/Harvest (Recent – Early)”?
Lines 428-430. This is certainly true, broadly speaking. However, there are studies, such as the long-term (started in 1936 and continued until today) study on permanent research plots in Białowieża National Park, NE Poland, that show that spruce is strongly declining also in stands characterized by significant age and species diversity. See Fig. 8 in Brzeziecki et al. 2020. Over 80 years without major disturbance .... J. Ecol. 108: 1138-1154. https://doi.org/10.1111/1365-2745.13367.
Line 443-444. “Together with the homogenising effects of salvage logging…”. Not very clear for me what do you mean by “homogenising effects of salvage logging”. For example, if salvage logging takes place in the initial period of insect outbreaks, then its effect is the creation of smaller or larger gaps in forest canopies, which lead to an increase in the structural diversity of the tree stands. These types of gaps make also possible introduction of more resistant tree species, either by natural regeneration or by planting.
Line 449. Tendency towards “accumulating high biomass over decades of growth” occurs also in the case of many natural forest types, for example in beech-dominated forest in Europe (see Schütz J.-Ph. 2002. Silvicultural tools to develop irregular…Forestry 75,4: 329-337.)
Line 500-501. “reducing susceptibility in high-risk stands”. It is not very clear what exactly is meant by that. Could you be more specific? What do you actually propose to do in the case of “high-risk stands”?